TM 55-1510-221-10 Table  2-2.  Fuel  Quantity  Data T A N K S NUMBER GALLONS **POUNDS Wing  Tanks 5 135 877.5 LEFT  ENGINE Nacelle   Tank 1 57 370.5 Auxiliary  Tank 1 79 513.5 Wing  Tanks 5 135 884.0 RIGHT ENGINE Nacelle   Tank 1 57 370.5 Auxiliary  Tank 1 79 513.5 *TOTALS 14 542 3523.0 * Unusable fuel quantity and weight (4 gallons, 26 pounds) not included in totals. * * Fuel weight is based on standard day conditions at 6.5 pounds per U.S. gallon. Total fuel system capacity is 542 gallons (usable). to  transfer  auxiliary  fuel  to  the  nacelle  tank  to  be consumed by the engine during the initial portion of the flight. When an engine is started, pressure at the engine driven boost pump closes a pressure switch which, after a  30  to  50  second  tie  delay  to  avoid  depletion  of  fuel pressure   during   starting,   energizes   the   motive   flow valve.  When  auxiliary  fuel  is  depleted,  a  low  level  float switch de-energizes the motive flow valve after a 30 to 60 second  time  delay  provided  to  prevent  cycling  of  the motive flow valve due to sloshing fuel.   In the event of a failure of the motive flow valve or the associated control circuitry, the loss of motive flow pressure when there is still fuel remaining in the auxiliary fuel tank is sensed by a  pressure  switch  and  float  switch,  respectively,  which illuminates  a  caution  annunciator  light  placarded  No.  1 NO FUEL XFR or No. 2 NO FUEL XFR. During engine start, the pilot should note that the NO FUEL XFR lights extinguish  30  to  50  seconds  after  engine  start.  The  NO FUEL  XFR  lights  will  not  illuminate  if  auxiliary  tanks are  empty.  A  manual  override  is  incorporated  as  a backup   for   the   automatic   transfer   system.   This   is initiated by placing the AUX TRANSFER switch, located on   the   FUEL   management   panel   to   the   OVERRIDE position.  This  will  energize  the  transfer  control  motive flow   valve.   The   transfer   systems   are   protected   by 5-ampere   circuit   breakers   placarded   AUXILIARY TRANSFER  No.  1  or  No.  2,  located  on  the  overhead circuit breaker panel (fig. 2-26), 2.0 inches high. NOTE In  turbulence  or  during  maneuvers,  the  NO FUEL   XFR   lights   may   momentarily illuminate  after  the  auxiliary  fuel  has completed  transfer. d.  Fuel  Gaging  System.  The  total  fuel  quantity  in the  left  or  right  main  system  or  left  or  right  auxiliary tank   is   measured   by   a   capacitance   type   fuel   gaging 2-32 Charge  4 system. Two fuel gages, one for the left and one for the right fuel system, read fuel quantity in pounds. Refer to Section  IX  for  fuel  capacities  and  weights.  A  maximum of  3%  error  may  be  encountered  in  each  system. However,  the  system  is  compensated  for  fuel  density changes  due  to  temperature  excursions.  In  addition  to the fuel gages, yellow No. 1 NAC LOW or No. 2 NAC LOW   lights   on   the   caution/advisory   annunciator panuminate  when  there  is  approximately  20  minutes  of fuel per engine remaining (on standard day, at sea level, normal cruise power consumption rate). The fuel gaging system   is   protected   by   individual   5-ampere   circuit breakers placarded QTY IND and QTY WARN No. 1 or No. 2, located on the overhead circuit breaker panel (fig. 2-26). A mechanical spiral float gage is installed in each auxiliary fuel tank to provide an indication of fuel level when  servicing  the  tank.  The  gage  is  installed  on  the auxiliary fuel tank cover, adjacent to the filler neck (fig. 2-13).  A  small  sight  window  in  the  upper  wing  skin permits observation of the gage. e.  Fuel  Management  Panel.  The  fuel  management panel  is  located  on  the  cockpit  overhead  between  the pilot and copilot.  It contains the fuel gages, standby fuel pump  switches,  the  crossfeed  valve  switch  and  a  fuel gaging  system  control  switch  and  transfer  control switches  are  also  installed. (1.) Fuel gaging system control switch. A switch on the  fuel  management  panel  (fig.  2-14)  placarded  FUEL QUANTITY,  MAIN  -  AUXILIARY,  controls  the  fuel gaging  system.  When  in  the  MAIN  position  the  fuel gages  read  the  total  fuel  quantity  in  the  left  and  right wing fuel system. When in the AUXILIARY  position  the fuel  gages  read  the  fuel  quantity  in  the  left  and  right auxiliary   tanks   only.